Boot into a previous version of Ubuntu to fix startup freeze

10 January, 2018 - 11:56
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If your Ubuntu installation locks up as the graphical boot screen attempts to initialize, and you can't get access to your system after starting it up, booting into a previous version can be a help.

This can happen after updating to the the latest update to Linux 4.4.0-108 kernel, which included a fix for the Meltdown vulnerability.

You should be able get back into Ubuntu again by going back to the previous working kernel version from GRUB, in this case 4.4.0-104-generic:

  • Reboot while holding down the Shift-key
  • Select Advanced options (second option) and hit Enter
  • Select 4.4.0-104-generic (third option) and hit Enter

The reason I include the position in the list is because my monitor has a huge resolution, making the text unreadable.

How to see your versions of CPU, Ubuntu and kernel:

$ cat /proc/cpuinfo

model name : Intel(R) Core(TM) i5-4590 CPU @ 3.30GHz

$ lsb_release -a

Description: Ubuntu 16.04.3 LTS

$ uname -a

Linux comp 4.4.0-104-generic #127-Ubuntu SMP Mon Dec 11 11:16:42 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

See also: https://ubuntuforums.org/showthread.php?t=2382157

EDIT: A new Ubuntu release has just been issued, so updating your system should result in kernel 4.4.0-109 getting installed, which seems to work for most people:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1742323
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1741934